Tanning material



Patented Sept. 6, 1938 UNITED Y STATES .TANNING MATERIAL 1;

" Alfred Russell and John w. Copenhayer, rundelphia, Pa., assignors toRohm & Haas Company, Philadelphia, Pa.

No'Drawlng. Application October so, 1937,

Serial No. 172.043

, 12 Claims. (Ci. 149-5) This invention relates to the production of,

new synthetic taiming materials that may be used in tanning skins, toretan leather made with other tanning materials, and to bleach andbrighten chrome leather.

- In our copending application Serial No. 161,066 filed August 26, 1937,it is shown that-excellent tanning materials especially useful forbleaching chrome leather can be made by condensing a dihydroxydiarylsulfone sulfonate with formaldehyde. In copending application,Serial-No. 172,042, filed on even date herewith, it is shown that thetanning and bleaching properties of these sulfone sulfonate-formaldehydecondenlfi sates can be improved by co-condensing urea and thesulfone-sulfonate with formaldehyde. We have also found that a similarimprovement is obtainable if instead of starting with the sulfonateddihydroxy diaryl -sulfone the unsulfon- 30 ated material is reactedwith'urea and formaldehyde and the resulting water insoluble condensatedispersed in an aqueous solution of an aromatic sulfonic acid, such asnaphthalene sulfonic acid.. When applied tothe bleaching the 35 chrometanned leather'these materialsgive a rapid and intensive surfaceretannage and an improved quality white leather that has a remarkableresistance to sunlight. In making the condensate the reaction is car- ;0ried out on the wild side of neutrality, preferably in concentratedhydrochloric acid or sulfuric acidof equivalent strength. The dihydroxydiarysulfone and urea may be dissolved in a strong aqueous. solution ofacid, the solution ;5 heated to a temperature at which. formaldehydecondenses readily with the sulfone and the urea, and the formaldehydeadded slowly while the mixture is being vigorously stirred. After allthe formaldehyde is added, heating at the to boiling point of thesolution with reflux of vaporized material is continued until reactionis complete. If desired, the formaldehyde may be added to the coldsolution of the sulfone and urea...

The relative proportion of urea, sulfone and formaldehyde that may beused varies over a wide range. The best ratio we have found is twomolecular equivalents each of formaldehyde and sulfoneto one molecularequivalent of urea.

These ratios webelieve give on condensation a molecule having theformula wherein the'Bs are similar or dissimilar dih i5 droxy diarylsulfone groups attached to the methylene groups by nuclear carbon atoms.Reducing the quantity of urea reduces the amount of this material in thefinal condensate and accordingly while permissible is not recommended.The formaldehyde maylikewise be reduced, par- 6 ticularly if less thanthe above stated amount, of urea is used. However, there-should be usedone mol. of formaldehydio'r each two mols of sulfone plus one mol. ofiormaldehyde for each mol.. or urea. Increasing the ratio of urea and 10formaldehyde leads to the formation of more complicated molecules but upto four mols of formaldehyde and up to two mols of urea to two mols ofsulfone may be used.

The tanning solution is prepared by adding the desired amount of thewater insoluble conden-v sate to an aqueous solution of naphthalenesulfonic acid and vigorously stirring, preferably while heating themixture. Heating to aid dispersion of the condensate is unnecessary butsubventiom- In these examples the parts given are so parts by weight.

Example 1.50 parts of 4:4 dihydroxy diphenyl sulfone was suspended in300 parts of 36% aqueous hydrochloric acid containing 6 parts of ureaand the suspension heated with vigorous stirring to 98-400 C. 20 partsof 30% aqueous formaldehyde was added slowly over 5 minutes and thewhole maintained at a temperature of 98-100 C. under reflux withvigorous stirring for 2 hours. At this time aninsoluble resin hadseparated. It was removed from the aqueous layer, washed twice withboiling water, and dried. 25 parts of this resinous material was addedto a solution of parts naphthalene sulfonic acid in 20 parts of waterand the mixture heated with 4,5 brisk stirring at C. until completesolution was obtained and the product was stable to indefinite dilutionwith water. The reaction mixture was diluted to a final mass of 200parts with water. This solution may be used directly for 50 tanning orit may, if so desired, be partially neutralized with alkali first andthen applied to tanning. I

Example2.--50 parts of 4:4 dihydroxydi phenyl sulfone was suspended in asolution of 100 parts 98% sulfuric acid dissolved in 175 parts of watercontaining 6 parts of urea. ,The suspension was heated to the boilingtemperature 'under reflux and 20 parts of 30% aqueous formaldehydeadded. The whole was maintained at the boiling temperature for 2 hours.At the end of this time the precipitated resin was collected, washedtwice with boiling water, dried, and dispersed in a solution ofnaphthalene sulfonic acid and water using the quantities and methoddescribed in Example 1.

The dihydroxy diphenyl sulfone used in these I examples can be replacedwith equivalent quantities of other dihydroxy diaryl sulfones such as apH of 4-4 when it may be oiled and finished in any recognized manner.The leather so produced has a white surface of remarkable resistance tothe action of strong sunlight.

. We claim:

l. The process of preparing a synthetic tanning material which comprisesco-condensing a dihydroxy diaryl sulfone and urea with formaldehyde instrong acid solution and dispersing the resinous material obtained in anaqueous solution of an aromatic sulfonic acid.

2. The process of preparing a synthetic tanning material which comprisesco-condensing a dihydroxy diphenyl sulfone and urea with formaldehyde instrong acid solution and dispersing the resinous material obtained in anaqueous sotion of an aromatic sulfonic acid.

3. The process of preparing a synthetic tanning material which comprisesco-condensing 4:4 dihydroxy diphenyl sulfone and urea with formaldehydein strong acid solution and dispersing the resinous material obtained inan aqueous solution of naphthalene sulfonic acid.

4. The process of preparing a synthetic tanning material which comprisesco-condensing substantially two molecular equivalents of a dihydroxydiphenyl sulfone and substantially one molecular equivalent of urea withsubstantially two molecular equivalents of formaldehyde and dispersingthe resinous material obtained in an aqueous solution of an aromaticsulfonic acid.

5. The process of preparing a synthetic tanning material which comprisesco-condensing substantially-two molecular equivalents of a dihydroxydiphenyl sulfone and substantially one molecular equivalent of urea withsubstantially two molecular equivalents of formaldehyde and dispersingthe resinous material obtained in an aqueous solution of naphthalenesulfonic acid.

6. A synthetic tanning material which is a joint condensation product ofa dihydroxy diaryl sulfone and urea with formaldehyde dispersed in anaqueous solution of an aromatic sulfonic acid.

'7. A synthetic tanning material which is a Joint condensation productof a'dihydroxy diaryl sulfone and 'urea. with formaldehyde dispersed inan aqueous solution of naphthalene sulfonic acid.

8'. A synthetic tanning material which is a joint condensation productof 4:4 dihydroxy diphenyl sulfone and urea with formaldehyde dispersedin an aqueous solution of naphthalene sulfonic acid.

9. A synthetic tanning material which is a joint condensation product ofsubstantially two molecular equivalents of a dihydroxy diphenyl sulfoneand substantially one molecular equivalent of urea with substantiallytwo molecular equivalents of formaldehyde dispersed in an aqueoussolution of an aromatic sulfonic acid.

10. A synthetic tanning material which is a joint condensation productof substantially two molecular equivalents of a dihydroxy diphenylsulfone and substantially one molecular equivalent of urea withsubstantially two molecular equivalents of formaldehyde dispersed in anaqueous solution of naphthalene sulfonic acid.

11. In a process of making leather the improvement which comprisestreating a chrome tanned leather with a joint condensation product of adihydroxy diphenyl sulfone, urea and-formaldehyde dispersed in anaqueous solution of naphthalene sulfonic acid.

12. In a process of making leather the improvement which comprisestreating a chrome tanned leather with a joint condensation product ofsubstantially two molecular equivalents of a dihydroxy diphenyl sulfone,substantially one molecular equivalent of urea, and substantially twomolecular equivalents of formaldehyde dispersed in an aqueous solutionof naphthalene sulfonic acid.

- ALFRED RUSSELL.

JOHN W. COPENHAVER.

I CERTIFICATE OF- CORRECTION. 7 Patent No, 2,129,55L September 6,19 8.

' ALFRED RUSSELL, ET AL. I

It is hereby certified that-error appears in the printed specificationof the above numbered patent requiring correction as follows:. Page 1,first column, line 2h, for the article "the" second occurrence, read of;line 55, for "diarysulfone" readdiarylsulfone; and second column,'line10, for "'or' read of; page Z, first column, line claim 2,'for thesyllable and words "tion of an aromatic" read lution of naphthalene; andthat the said Letters Patent shonld be'read with this correction thereinthat the same mayconform to the record of the case in the Patent Office.

Signed and sealed this 10th day of January, A. D. 1959.

